小麦钙调素基因TaCaM1分子特征及转化烟草植株对低磷胁迫的反应

Molecular characterization of calmodulin gene TaCaM1 and the response of transformed tobacco plants to low phosphorus stress

钙信号转导途径在介导植物应答和适应环境逆境中发挥重要作用。本试验以前期鉴定的对低磷逆境产生应答的小麦钙调素基因TaCaM1为基础,对该基因分子特征、应答低磷胁迫表达模式及介导植株抵御低磷逆境的生物学功能进行了研究。结果表明,TaCaM1基因与部分植物种属CaM家族基因高度同源,基因编码蛋白含有植物种属CaM家族蛋白含有的保守结构域,该基因翻译蛋白经内质网分选后定位在细胞质中。低磷胁迫下,根系中该基因的转录本数量随胁迫进程不断减少,复磷后低磷下调的基因表达不断上调。基因转化结果表明,丰磷条件下,上、下调表达株系的植株生长、干鲜重、含磷量和磷累积量以及细胞保护参数与野生型对照相比表现相似;低磷处理下,与对照相比,转化株系的植株生长和上述生理生化参数发生明显改变,表现为正义系Sen-1植株长势变差,磷累积量减少,部分保护酶活性下降,丙二醛含量增加;而反义系Anti-1植株长势增强,磷累积量增多,细胞保护酶活性提高,丙二醛含量减少。研究表明,TaCaM1通过下调响应低磷逆境,在植株抵御低磷逆境中发挥重要的负调控效应。

The signaling pathway associated with calcium cues plays an important role in mediating plant responses and tolerance to environmental stresses.In this study,using TaCaM1,a calmodulin(CaM)family genes in wheat that was shown to be differentially expressed upon low-P stress,we investigated the molecular characterization,expression patterns upon P deprivation,and function in mediating plant adaptation to P starvation stress of this gene.Results indicated that TaCaM1 is homologous to its plant counterparts.The TaCaM1 protein contains conserved domains shared by plant CaM proteins.After endoplasmic reticulum(ER)assortment,TaCaM1 targets onto the cytoplasm which exerts biological functions.Upon low-P stress,the transcripts of TaCaM1 were gradually downregulated in roots along with low-P treatment progression.Moreover,the P-deprived expression of this wheat gene was gradually recovered following the normal P recovery conditions.Transgene analysis revealed that under normal P supply conditions,plant growth,fresh and dry weights,P concentration and accumulative amounts,and antioxidant enzyme activities in transgenic lines were all similar to those in wild type.However,under low-P treatments,dramatic alterations were shown in the transgenic lines and wild type plants,in which the TaCaM1 overexpressing line designated as Sen-1 was shown to deteriorate in plant growth,P accumulation,and activities of some antioxidant enzymes,together with the increased MDA contents.In contrast,the line with TaCaM1 knockdown referred to as Anti-1 was found to be improved in plant growth,P accumulation,antioxidant enzyme activities and together with less accumulative MDA.Our results suggested that TaCaM1 plays a critical role in negatively regulating plant P deprivation adaptation through its depressed response to this stressor.